RU2269397C1 - Profiled milling method - Google Patents

Abstract

FIELD: metal working, in particular, working of rolling surface profile of wheel pairs for railway transport.

SUBSTANCE: method involves transmitting rotational motion and feeding motion to profile cutter mounted on holder and to blank; using cutter located on mandrel for rotation in slider bearings formed as bushings and in thrust roller bearings. One end of cutter is made corrugated for joining to mated corrugated end of coupling mounted on mandrel in slots for axial displacement and biased by nut to cutter with the help of damping member formed as disk spring. Other end of cutter is biased with the help of nut through one of thrust roller bearings. Before machining, resiliency of damping member may be regulated for increasing resistance to vibration, providing continuous-intermittent bringing into contact and separation of cutter teeth from contact with surface under machining process, said surface having thermomechanical and other defects.

EFFECT: increased durability, enhanced reliability in operation and increased efficiency.

3 cl, 7 dwg

Description

The invention relates to metal working, to mechanical engineering technology, in particular to milling by shaped cutters, and can be used, for example, for processing the profile of the rolling surface of railway wheelset pairs.

A known method of milling a combined cutter containing a body with cutters, damping elements made in the form of thin-walled bushings, and an intermediate disk [1].

The disadvantage of this method is the limited technological capabilities, since the cutter is intended only for machining planes and does not allow machining bodies of revolution and surfaces of complex shape, which are obtained on CNC machines or using a copier, as well as the complexity of the design, assembly and tuning of the tool - all this makes the milling process expensive and inefficient.

There is a method of shaped milling of surfaces of revolution, in which a shaped milling cutter mounted on a mandrel is used, while the workpiece and milling cutter are informed of a rotational movement and a feed motion [2].

The disadvantage of this method is the limited technological capabilities, since the cutter does not respond to thermomechanical and other damages encountered in the workpiece and causing vibrations and shock-discontinuous processing, which reduces the quality and productivity of processing, as well as tool breakage.

The objective of the invention is the expansion of technological capabilities for processing bodies of revolution and surfaces of complex shape, as well as simplifying the design, assembly and tuning of the tool, increasing productivity, machining quality and resistance of the cutter by ensuring a smooth embedding process and translating the kinetic energy of the impact into the potential bending energy of an elastic disk spring .

The problem is solved using the proposed method of shaped milling of surfaces of revolution, in which the shaped milling cutter mounted on the mandrel and the workpiece informs the rotational movement and feed movement, using a milling cutter mounted on the mandrel with the possibility of rotation in sliding bearings in the form of bushings and thrust rolling bearings moreover, one end of the cutter is made corrugated for interfacing with the counter corrugated end face of the coupling mounted on the mandrel on the slots movably in the axial direction and preloaded with oschyu nut cutter to the damping element in the form of a plate spring, and wherein the second cutter end is preloaded nut through one of said thrust rolling bearings. In addition, before processing, the elasticity of the damping element is adjusted to increase vibration resistance, reliability and ensure smoothly intermittent entry and exit of the cutter teeth from contact with the treated surface, which has thermomechanical and other damages. Moreover, the method is intended for processing the profile of the surface of the rolling wheelsets of railway vehicles.

The essence of the method is illustrated by drawings.

Figure 1 shows the proposed device for attaching a shaped cutter that implements the proposed method, General view of the Assembly, a partial longitudinal section; figure 2 is a section aa in figure 1; figure 3 is a section bB in figure 1; figure 4 is a cross-section bb in figure 1; figure 5 - element D in figure 1; figure 6 is a diagram of the processing profile of the surface of the rolling wheels of a railway vehicle; in Fig.7 is a section GG in Fig.6.

The proposed method is intended for processing a shaped milling cutter 1 of the profile of the rolling surface of the wheels 2 of railway transport, in which the counter-rotational motion and the movement of the transverse feed are reported to the workpiece and milling cutter.

A device that implements the proposed method contains a mandrel 3 on which a shaped cutter 1 and a damping element 4 are installed. The damping element 4 is taken in the form of a disk spring (for example, according to GOST 3057-79) of great stiffness made of spring steel (GOST 14963-78 )

The mill 1 is mounted on the mandrel 3 with the possibility of rotation on sliding bearings in the form of bushings 5 and thrust rolling bearings 6 and 7. One end (for example, left, see figure 1) of the mill 1 is made corrugated with radial triangular flutes 8, the profile angle of which equal to 90 °. This end of the cutter 1 is mated with a counter profile made of grooved radial triangular flutes 9 at the end of the coupling 10. The coupling 10 is mounted on the mandrel 3 on the splines 11 movably in the axial direction and pressed against the mill 1 by a disk spring 4 using a nut 12 and a lock nut 13.

The axial force created by the Belleville spring 4 is received through the clutch 10 and the mill 1 by a thrust rolling bearing 6, which is made in the form of bored tracks for balls on the second end of the mill and on the end of the nut 14, the latter is fixed from self-unscrewing by the lock nut 15. The raceways of the angular contact ball bearings 7 are made on the mandrel 3 and in the hole of the cutter 1.

This design of bearings 6 and 7 allows to reduce the dimensions of the device, however, as bearings 6 and 7 can be taken standard, respectively, thrust and angular contact ball bearings.

A method for processing a prefabricated cutter 1, in which the desired shaped profile is created as an envelope curve for a set of simple-shaped edges of its individual cutting elements, is intended for processing the profile of the rolling surface of railway wheelset pairs.

The mill [2] consists of a body, in the grooves of which are mounted rails with round hard alloy plates fixed to them with a diameter of 12 ... 16 mm. To obtain the necessary roughness of the machined surface, the nests for plates on adjacent rails are offset from each other by 1.5 ... 2 mm.

The proposed method of processing with a shaped combined mill allows self-adaptation to the heterogeneity of the processed material, to fluctuations in the allowance and other thermomechanical damages that cause an increase in cutting force, and to reduce impact loads on the teeth of the tool during processing, which will increase the durability of the cutting elements.

An additional degree of freedom - turning relative to the longitudinal axis, allows the tooth that came into contact with the workpiece to reduce the angle of rotation of the cutter under the action of the increased cutting force, thereby reducing the thickness of the chip removed.

The reduction in the angle of rotation of the cutter occurs due to the extraction of the coupling 10 and the instantaneous stop of the cutter with continuous and uniform rotation of the mandrel and the workpiece. Thus, when faced with an increased allowance or thermomechanical damage on the treated surface, the device with the cutter 1 will react and the flutes 9 of the coupling 10 will disengage from the flutes 8 of the cutter 1, the cutter will begin to slip relative to the coupling.

After passing the area with increased cutting force, slippage will stop and the cutter will continue to rotate uniformly, driven by the coupling.

When the accepted angle of 90 ° of the triangular grooves 8 and 9, the ratio of the cutting force P _z at optimal cutting conditions and the pressing force of the coupling R _d to the cutter due to the elasticity of the damper 4 is as follows:

- at P _z <P _d - the normal operation of the cutter is observed, without slipping and clicks;

- when P _z > P _d - the cutter slips relative to the coupling and characteristic clicks are heard.

The method depicted in figures 1-7, is intended for processing the profile of the surface of the rolling wheelsets of railway vehicles, however, it can be effectively used for shaping milling any surfaces of various workpieces.

For machining, when restoring the profile of the rolling surface of railway wheelsets, a different cutting tool is used, for which replaceable plates of different shape and composition are used for the cutting part.

The main obstacle to the effective use of the tool is the thermomechanical and other damage to the wheel rim that occurs during operation [2].

When the cutter rotates at a constant speed at the time of cutting the tooth into the workpiece at a place of increased hardness, the circumferential feed rate V _{f of the} cutting tooth of the cutter decreases due to the bending of the elastic damper - Belleville spring and the width of the chip removed. This ensures a smooth embedding process and the transition of the kinetic energy of the impact into the potential energy of the bend of the elastic disk spring.

After the tooth comes out of contact with the workpiece, the previously deformed elastic element returns to its original state, restoring the engagement of the coupling riffles with the cutter riffles.

Due to the presence of an elastic damper, with which the speed of the peripheral feed V _{f of the} cutter is reduced, a smoothly intermittent entry and exit of the cutter teeth out of contact with thermomechanical and other damages to the processed surface is ensured.

Example. During production tests, the rolling surface of the wheelset of the railway transport with thermomechanical damages was processed, the diameter of the wheel blank was 1009 mm, the diameter of the finished parts after processing was 995 mm, the processing was carried out in one pass, so the milling depth was 7 mm.

Induction annealing was carried out before mechanical treatment of the rolling surface; the average hardness in the rolling circle after heat treatment was 289 HB. The wheel is made of grade 2 steel in accordance with GOST 10791-89 steel chemical composition: C - 0.60%; Mn - 0.78%; Si - 0.31%; P - 0.03%; S - 0.03%, the rest is iron.

Machining modes: rotation speed of the wheel blank - V _s = 5 m / min (n _s = 1.6 min ^-1 ); cutter rotation speed - V _f = 342 m / min (n _and = 320 min ^-1 ). Shaped mill installed by the proposed method had the number of teeth z = 10; outer diameter - 340 mm; cup plates RPUX2710MO of hard alloy T14K8.

Processing was carried out on a modernized wheel-turning lathe machine mod. KZh 1836 (manufactured at Kramatorsky KZTS).

Tests established that, with the same performance, the durability of the tool working according to the proposed method increased by 2 ... 2.5 times compared with traditional processing, the surface roughness improved and the vibration resistance of the process increased, productivity increased and marriage was reduced.

Information sources

1. A.S. 1569105 USSR, MKI 5 V 23 C 5/06. Team cutter. V.I. Petrov and others. Application No. 4340167 / 31-08, head. 12/07/88, publ. 06/07 90. Bull. No. 21.

2. Bogdanov A.F. and others. Restoring the profile of the surface of the rolling wheelsets. S-Pb, PGUPS, 2000, S.50-54, Fig.2.7. - prototype.

Claims (3)

1. The method of shaped milling of the surfaces of rotation, in which the shaped milling cutter mounted on the mandrel and the workpiece informs the rotational movement and feed movement, characterized in that they use a milling cutter mounted on the mandrel with the possibility of rotation in sliding bearings in the form of bushings and thrust rolling bearings, moreover, one end of the cutter is made corrugated to mate with the counter corrugated end of the coupling mounted on the mandrel on the slots movably in the axial direction and pressed with a nut to the cutter by a damping element volume in the form of a Belleville spring, while the second end of the cutter is tightened by a nut through one of the mentioned thrust rolling bearings. 2. The method according to claim 1, characterized in that before processing, the elasticity of the damping element is adjusted to increase vibration resistance, reliability and ensure smoothly intermittent entry and exit of the cutter teeth from contact with the treated surface, which has thermomechanical and other damages. 3. The method according to claim 1, characterized in that it is intended for processing the profile of the surface of the rolling wheelsets of railway vehicles.

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